Radial location of bearings
If the load carrying ability of a bearing is to be fully utilized, its rings or washers must be fully supported around their complete circumference and across the entire width of the raceway. The support, which must be firm and even can be provided by a cylindrical or tapered seat or, for thrust bearing washers, by a flat (plane) support surface. This means that bearing seats must be made with adequate accuracy and that their surface should be uninterrupted by grooves, holes or other features. In addition, the bearing rings must be reliably secured to prevent them from turning on or in their seats under load.
Generally speaking, satisfactory radial location and adequate support can only be obtained when the rings are mounted with an appropriate degree of interference. Inadequately or incorrectly secured bearing rings generally cause damage to the bearings and associated components. However, when easy mounting and dismounting are desirable, or when axial displacement is required with a non-locating bearing, an interference fit cannot always be used. In certain cases where a loose fit is employed it is necessary to take special precautions to limit the inevitable wear from creep, as for example, by surface hardening of the bearing seat and abutments, lubrication of the mating surfaces via special lubrication grooves and the removal of wear particles, or slots in the bearing ring side faces to accommodate keys or other holding devices.